1. Field of the Invention
The present invention relates to an image forming apparatus to which a replaceable replacement unit is detachably loaded.
2. Description of the Related Art
Some conventional image forming apparatuses facilitate maintenance by a user, by making consumables such as a photosensitive drum or toner a replaceable unit to the main body of the image forming apparatus. In addition, recently, with the objective of improving image quality or accurately controlling service life of a replacement unit, replacement units having a memory element to/from which such information can be written/read have emerged. The writing/reading of data to/from the memory element mounted in the replacement unit is usually performed with it connected to the main body of the image forming apparatus through a connector. However, such a configuration suffers from the problem that signals to the memory element are weak and even a venial loose connection causes a malfunction.
Hence, as a memory element to be mounted in said replacement unit, a wireless IC tag has been proposed so that writing/reading of data can be performed in non-contact manner.
In Japanese Patent Application Laid-Open (JP-A) No. 2000-246921 publication (hereinafter referred to as Patent Document 1), an IC chip having stored therein information such as data on identification with an image forming apparatus, ink level, etc. is loaded in a replaceable ink cartridge. Then, an image forming apparatus to which said cartridge can be detachably loaded comprises a reader/writer associated with said IC chip. The configuration and the technologies disclosed in the Patent Document 1 could enable the image forming apparatus itself and said IC chip to communicate said information in non-contact manner, with the cartridge loaded onto the image forming apparatus.
In addition, in JP-A No. 2001-22230 publication (hereinafter referred to as Patent Document 2), non-contact communication IC tags are respectively mounted in a plurality of replaceable cartridges. It also discloses the configuration in which one reader/writer capable of transmitting/receiving information to/from the respective said IC tags in non-contact manner is provided on the main body of the image forming apparatus to which said cartridges are detachably loaded.
In the technology described the Patent Documents mentioned above, however, since communication with an IC tag mounted in a replacement unit takes place in non-contact manner, electromagnetic radiation noise may possibly leak to the outside of the apparatus during communication thereof. In addition, according to the international standard, intensity of the electromagnetic radiation noise leaking from the apparatus must be reduced below a certain limit.
In the technology disclosed in Patent Document 2, in particular, non-contact communication IC tags that are separately mounted in a plurality of replacement units are deployed in a relatively wide range, wherein one reader/writer is responsible for communication with these IC tags. In other words, as communication distance between the said respective IC tags deployed in a relatively wide range and the one reader/writer increases, output level of radio wave necessary for transmission/reception of information should be set higher. Thus, there is fear that leakage of the electromagnetic radiation noise described above will relatively increase.